Aspirator systems are widely used in the health care industry and this context has been chosen to illustrate the present invention. The aspirator system of this invention however can be used in numerous applications, and this invention is not meant to be confined merely to health care uses.
In typical patient care aspirator systems a lumen is inserted into a patient's lungs, surgical wound, or any area requiring the removal of fluids or suspended solids. The lumen spreads the vacuum of the system over a sufficiently wide content area to minimize tissue damage to the patient. The lumen is typically connected to a vacuum source, and the material to be removed is thereby pulled by the vacuum into the lumen, through connecting tubing, and ultimately disposed of through conventional means, such as an in-line collection receptacle.
Often the material to be removed from the patient is of a non-uniform consistency. As a result, certain portions of the material can be easily drained using a low vacuum while other portions require a higher vacuum. Aspirator systems can therefore clog as they encounter matter requiring more suction than what was previously necessary.
In this application, the term "low vacuum" will refer to an absolute pressure close to, but less than atmospheric pressure, and "high vacuum" will refer to an absolute pressure level closer to zero absolute pressure than the pressure level denominated "low vacuum."
When clogging occurs, some systems must be shut down, cleared of the obstructing material, and reactivated. Unclogging an aspirator system in this way is cumbersome, increases labor costs, and results in substantial delays. Also, some unclogging procedures can increase the risk of spreading bacteria to the patient and to the hospital environment.
One apparent solution to the clogging problem would be merely to use a higher vacuum in the system. However, such increases in vacuum must typically be controlled very carefully, because too high a vacuum may cause significant injury to the patient and damage tissue surrounding the area being suctioned. A vacuum of sufficient intensity to prevent clogging will often damage surrounding tissue once the clogging material clears the system.
Another solution would be to increase the vacuum only so long as is necessary to unclog the system, and then reduce the vacuum to normal operation. However, many conventional systems cannot be accurately controlled to increase and decrease vacuum on a demand basis.
In some conventional systems, vibration and normal handling can cause vacuum fluctuations. Also, many conventional systems are unable to maintain a steady vacuum over extended periods of time. Such systems require additional monitoring to prevent the originally set vacuum from straying to an unacceptable level, higher or lower. Some conventional systems leak vacuum at different rates under different conditions and are therefore unreliable.
Also, some systems do not accurately monitor the system vacuum, and therefore the operator may not know whether or not the appropriate vacuum is being applied. Although some systems are able to accurately control and monitor the vacuum, such systems are often very expensive. Health care costs in general are increasing, and consequently cost effective alternatives to expensive health care procedures and devices are becoming more important as time goes on.
And finally, conventional systems do not include means which operate automatically in response to attainment of an undesirable vacuum level to prevent vacuum build-up past a fixed level. If, for example, a system malfunctions to the point where the vacuum level is too high, damage to a hydrophobic filter used in the aspirator system, as well as tissue damage, can result. Thus, the existence of an undesirably high vacuum could cause a filter in the hydrophobic filter to tear, or contaminants might be sucked through the filter membrane.
Accordingly, it is an object of this invention to provide an inexpensive aspirator system wherein the system vacuum can be accurately controlled.
A further object of this invention is to provide an aspirator system in which the vacuum ca be easily maintained at a vacuum level which will not harm the patient.
A further object of this invention is to create an aspirator system which can be quickly and easily adjusted by an operator to increase the vacuum just enough to unclog the system and thereafter to quickly return the system to a "just sufficient" vacuum level.
A further object of this invention is to provide an aspirator system which provides a steady vacuum over time without the need for periodic adjustment.
Yet another object of this invention is to provide mean of limiting the maximum vacuum level that can be administered by means of appropriate vacuum relief orifices.
A further object of this invention is to provide an aspirator system which is effective, durable, inexpensive, and easy to manufacture and repair.
Other objects and features of the invention will become apparent to those skilled in the art from the following specification when read in the light of the annexed drawings.